Morphine is a well known narcotic analgesic having the structural formula: ##STR1## Morphine and its structurally related relatives are extremely effective for the relief of moderate to severe pain, however, these compounds are narcotic and most possess dependence-inducing liability and other side effects such as emesis, constipation, sweating, respiratory depression and myosis which make them less than ideal analgesics. A compound with the appropriate profile of analgesic (agonist) and narcotic antagonist activity has potential for treatment of moderate to severe pain without the liability of drug dependence or drug abuse. A compound having the desired profile, 17-cyclobutylmethyl-3-hydroxy-8.beta.-methyl-6-methylene-morphinane, is disclosed in copending application Ser. No. 138,102, filed Apr. 21, 1980. This compound is well suited for use as a strong analgesic because of its agonist/antagonist profile.
Compounds of the type under consideration herein can be administered in the form of their free base, however, in many cases they are converted to their acid addition salts to increase their water solubility. Increased water solubility is desirable because it aids in the formulation of aqueous solutions for parenteral administration and assures a more rapid and uniform absorption or oral administration.
While the conversion of compounds of this type to their acid addition salts is known to have an effect on solubility, it cannot be predicted what effect a particular acid will have on the solubility of any specific compound.